11,578 research outputs found
Renormalization of the N=1 Abelian Super-Chern-Simons Theory Coupled to Parity-Preserving Matter
We analyse the renormalizability of an Abelian N=1 super-Chern-Simons model
coupled to parity-preserving matter on the light of the regularization
independent algebraic method. The model shows to be stable under radiative
corrections and to be gauge anomaly free.Comment: Latex, 7 pages, no figure
Teleparallel Spin Connection
A new expression for the spin connection of teleparallel gravity is proposed,
given by minus the contorsion tensor plus a zero connection. The corresponding
minimal coupling is covariant under local Lorentz transformation, and
equivalent to the minimal coupling prescription of general relativity. With
this coupling prescription, therefore, teleparallel gravity turns out to be
fully equivalent to general relativity, even in the presence of spinor fields.Comment: 2 pages, RevTeX, to appear in Phys. Rev D (Brief Report
Gravitation and Duality Symmetry
By generalizing the Hodge dual operator to the case of soldered bundles, and
working in the context of the teleparallel equivalent of general relativity, an
analysis of the duality symmetry in gravitation is performed. Although the
basic conclusion is that, at least in the general case, gravitation is not dual
symmetric, there is a particular theory in which this symmetry shows up. It is
a self dual (or anti-self dual) teleparallel gravity in which, due to the fact
that it does not contribute to the interaction of fermions with gravitation,
the purely tensor part of torsion is assumed to vanish. The ensuing fermionic
gravitational interaction is found to be chiral. Since duality is intimately
related to renormalizability, this theory may eventually be more amenable to
renormalization than teleparallel gravity or general relativity.Comment: 7 pages, no figures. Version 2: minor presentation changes,
references added. Accepted for publication in Int. J. Mod. Phys.
Future dynamics in f(R) theories
The gravity theories provide an alternative way to explain the current
cosmic acceleration without invoking dark energy matter component. However, the
freedom in the choice of the functional forms of gives rise to the
problem of how to constrain and break the degeneracy among these gravity
theories on theoretical and/or observational grounds. In this paper to proceed
further with the investigation on the potentialities, difficulties and
limitations of gravity, we examine the question as to whether the future
dynamics can be used to break the degeneracy between gravity theories by
investigating the future dynamics of spatially homogeneous and isotropic dust
flat models in two gravity theories, namely the well known gravity and another by A. Aviles et al., whose motivation comes
from the cosmographic approach to gravity. To this end we perform a
detailed numerical study of the future dynamic of these flat model in these
theories taking into account the recent constraints on the cosmological
parameters made by the Planck team. We show that besides being powerful for
discriminating between gravity theories, the future dynamics technique
can also be used to determine the fate of the Universe in the framework of
these gravity theories. Moreover, there emerges from our numerical
analysis that if we do not invoke a dark energy component with
equation-of-state parameter one still has dust flat FLRW solution
with a big rip, if gravity deviates from general relativity via . We also show that FLRW dust solutions with do not
necessarily lead to singularity.Comment: 12 pages, 8 figures. V2: Generality and implications of the results
are emphasized, connection with the recent literature improved, typos
corrected, references adde
Torsion and Gravitation: A new view
According to the teleparallel equivalent of general relativity, curvature and
torsion are two equivalent ways of describing the same gravitational field.
Despite equivalent, however, they act differently: whereas curvature yields a
geometric description, in which the concept of gravitational force is absent,
torsion acts as a true gravitational force, quite similar to the Lorentz force
of electrodynamics. As a consequence, the right-hand side of a
spinless-particle equation of motion (which would represent a gravitational
force) is always zero in the geometric description, but not in the teleparallel
case. This means essentially that the gravitational coupling prescription can
be minimal only in the geometric case. Relying on this property, a new
gravitational coupling prescription in the presence of curvature and torsion is
proposed. It is constructed in such a way to preserve the equivalence between
curvature and torsion, and its basic property is to be equivalent with the
usual coupling prescription of general relativity. According to this view, no
new physics is connected with torsion, which appears as a mere alternative to
curvature in the description of gravitation. An application of this formulation
to the equations of motion of both a spinless and a spinning particle is madeComment: To appear on IJMP
- …